Field of the Invention
Embodiments of the present invention generally relate to valves for use in downhole pumps.
Description of the Related Art
Pumps can be used in wells to help bring production fluids (such as gas or other hydrocarbons) to the surface. This is often referred to as providing artificial lift, as the reservoir pressure is insufficient for the production fluid to reach the surface on its own.
One type of pump for such operations is a hydraulically-actuated double-acting piston pump. This type of pump is typically deployed downhole in tubing, which is disposed in a wellbore casing. Surface equipment injects power fluid (e.g., produced water or oil) down the tubing to the pump. The power fluid operates to drive an engine piston internally between upstrokes and downstrokes which, in turn, drives a pump piston connected to the engine piston via a rod.
During alternating strokes, the pump simultaneously draws in production fluid into the tubing and discharges production fluid out of the tubing. The production fluid discharged from the pump accumulates and rises to the surface for handling.
Hydraulic piston pumps often include check valves to control production fluid flow during the upstrokes and downstrokes. Assuming a pump that operates in a manner described above, a first check valve discharges production fluid during an upstroke while a second check valve collects production fluid. During a downstroke, the first check valve collects production fluid while the second check valve discharges production fluid.
There is a need for improved check valves to control production fluid flow during the strokes of the pump.